Influence of spray-drying, freeze-drying and vacuum-drying on physicochemical and functional properties of gelatin from Labeo rohita swim bladder.

Influence of different drying method on yield, physicochemical and functional properties of gelatin from rohu (Labeo rohita) swim bladder were investigated. Freeze-drying presented the highest gelatin yield (54.51 g/100 g, dry weight basis), followed by vacuum-drying (48.95 g/100 g) and spray-drying (41.76 g/100 g), respectively (P < 0.05). All gelatin samples showed glycine as the major amino acid followed by proline, glutamic acid, alanine, arginine and hydroxyproline, respectively. Freeze-dried gelatin (FDG) and spray-dried gelatin (SDG) showed α (α1 and α2), ß-chains and γ-chain as the predominant components, whereas an absence of ß- and γ-chains found in vacuum-dried gelatin (VDG). FTIR spectra revealed that the loss of the triple-helix was found in all gelatins which indicated the conversion of collagen to soluble gelatin. FDG and SDG had the highest surface hydrophobicity, protein solubility, emulsifying, foaming and gelation property than VDG (P < 0.05). Moreover, SDG showed slightly higher surface hydrophobicity, protein solubility, emulsifying and foaming properties as compared to FDG (P < 0.05). However, no significant difference was found in gelation properties of FDG and SDG (P > 0.05). Therefore, freeze-drying or spray-drying could be an appropriate drying method for preparation of gelatin from rohu swim bladder with better functionalities.

Recovery and characterization of proteins from pangas (Pangasius pangasius) processing waste obtained through pH shift processing.

Study was conducted to recover proteins from pangas (Pangasius pangasius) processing waste (fillet frames) using pH shift method and to characterize the recovered isolates. pH 2.0 from acidic range and pH 13.0 from alkaline range were found to have maximum protein recovery (p < 0.05). During the recovery process, acidic pH (pH 2.0) was found to have minimal effect on proteins resulting in more stable isolates and strong protein gels. Alkaline pH (pH 13.0) caused protein denaturation resulting in less stable proteins and poor gel network. Both acidic and alkaline-aided processing caused significant (p < 0.05) reductions in total lipid, myoglobin, and pigment content thus by resulting in whiter protein isolates and gels. The content of total essential amino acids increased during pH shift processing, indicating the enrichment of essential amino acids. No microbial counts were detected in any of the isolates prepared using acid and alkaline extraction methods. pH shift processing was found to be promising in the utilization of fish processing waste for the recovery of functional proteins from pangas processing waste thus by reducing the supply demand gap as well pollution problems.

Assessment of DNA degradation induced by thermal and UV radiation processing: implications for quantification of genetically modified organisms.

DNA quality is an important parameter for the detection and quantification of genetically modified organisms (GMO's) using the polymerase chain reaction (PCR). Food processing leads to degradation of DNA, which may impair GMO detection and quantification. This study evaluated the effect of various processing treatments such as heating, baking, microwaving, autoclaving and ultraviolet (UV) irradiation on the relative transgenic content of MON 810 maize using pRSETMON-02, a dual target plasmid as a model system. Amongst all the processing treatments examined, autoclaving and UV irradiation resulted in the least recovery of the transgenic (CaMV 35S promoter) and taxon-specific (zein) target DNA sequences. Although a profound impact on DNA degradation was seen during the processing, DNA could still be reliably quantified by Real-time PCR. The measured mean DNA copy number ratios of the processed samples were in agreement with the expected values. Our study confirms the premise that the final analytical value assigned to a particular sample is independent of the degree of DNA degradation since the transgenic and the taxon-specific target sequences possessing approximately similar lengths degrade in parallel. The results of our study demonstrate that food processing does not alter the relative quantification of the transgenic content provided the quantitative assays target shorter amplicons and the difference in the amplicon size between the transgenic and taxon-specific genes is minimal.

A calibrator plasmid for quantitative analysis of insect resistant maize (Yieldgard MON 810).

Real-time PCR (RT-PCR) is the preferred method for the quantification of genetically modified organisms (GMOs) and implementation of labeling regulations. The precision, sensitivity, and reproducibility of RT-PCR data depend on the use of external calibrators. In this investigation, a dual target plasmid designated pRSETMON-02 comprising of MON 810 maize event specific and endogenous zein gene sequences in 1:1 ratio in tandem was constructed and validated. Commutability of plasmid DNA (pDNA) and genomic DNA (gDNA) calibrators for the quantification of MON 810 maize was assessed by employing a TaqMan RT-PCR targeting the P-35S and zein gene. Higher PCR efficiencies, good linearity and lower relative standard deviation (RSD) values were associated with pRSETMON-02 as opposed to gDNA calibrants. pDNA calibrants exhibited better performance characteristic in terms of closeness to the expected value of unknown samples than their genomic counterparts. Short term stability study of the pRSETMON-02 plasmid stored at different temperatures showed that pDNA is stable for 45 days at -20, and 4 °C. The results demonstrated that the developed dual target plasmid pRSETMON-02 is fit for the intended use of quantifying MON 810 maize and is a better alternative to conventional seed powder calibrants.

Detection and identification of genetically modified EE-1 brinjal (Solanum melongena) by single, multiplex and SYBR® real-time PCR.

BACKGROUND: Brinjal is an important vegetable crop. Major crop loss of brinjal is due to insect attack. Insect-resistant EE-1 brinjal has been developed and is awaiting approval for commercial release. Consumer health concerns and implementation of international labelling legislation demand reliable analytical detection methods for genetically modified (GM) varieties. RESULTS: End-point and real-time polymerase chain reaction (PCR) methods were used to detect EE-1 brinjal. In end-point PCR, primer pairs specific to 35S CaMV promoter, NOS terminator and nptII gene common to other GM crops were used. Based on the revealed 3' transgene integration sequence, primers specific for the event EE-1 brinjal were designed. These primers were used for end-point single, multiplex and SYBR-based real-time PCR. End-point single PCR showed that the designed primers were highly specific to event EE-1 with a sensitivity of 20 pg of genomic DNA, corresponding to 20 copies of haploid EE-1 brinjal genomic DNA. The limits of detection and quantification for SYBR-based real-time PCR assay were 10 and 100 copies respectively. CONCLUSION: The prior development of detection methods for this important vegetable crop will facilitate compliance with any forthcoming labelling regulations.